Method for transforming normal-pressure liquid dangerous cargo tank truck with volume exceeding standard

Abstract

The invention discloses a transformation method for a normal-pressure liquid dangerous cargo tank car with the volume exceeding the standard. The method comprises the following steps: firstly, accurately measuring the actual volume of the tank car by adopting a weighing method, comparing the actual volume with a marked volume, and calculating the volume difference required to be adjusted; and then, based on a calculation result, a proper hole opening position on the swash plate is determined. The hole is formed in the designated position of the swash plate, and the vent hole above the position is blocked, so that a closed gas phase space can be formed in the area above the hole forming position of the bin in the filling process, liquid in the bin is prevented from continuously rising during filling, and the volume of the tank car is accurately reduced. According to the method, the tank does not need to be welded, the internal structure of the tank is not changed, transformation is achieved only by adjusting the positions of the vent holes of the swash plate, and compared with a traditional method, the method has the advantages of being easy and convenient to operate, economical, efficient, high in adaptability and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of petrochemical industry, and in particular relates to a method for modifying a normal pressure liquid dangerous goods tank truck with excessive volume. Background Art

[0002] As a key tool for energy transportation, the number of atmospheric pressure tank trucks for dangerous liquids (hereinafter referred to as "atmospheric pressure tank trucks") has continued to grow in recent years. Since atmospheric pressure tank trucks usually transport flammable, explosive, harmful or highly corrosive liquids, their potential safety risks cannot be ignored. Among them, the overloading problem caused by excessive volume is particularly prominent. Due to the particularity of the transportation of liquid dangerous goods tank trucks, if the tank is not full, the liquid dangerous goods will shake in the tank during transportation, causing the vehicle to have inertia, unstable center of gravity, and difficulty in starting and braking; when turning, it is easy to roll over; the friction inside the tank increases, the air pressure increases, and there are serious accident hazards. At the same time, considering the economic benefits of transportation, atmospheric pressure tanks transporting dangerous liquid goods are generally transported according to the maximum allowable filling volume. In this case, the "small car and large tank" vehicle must be overloaded. This "essential overloading" situation increases the risk of accidents and possible serious consequences. Therefore, whether from a legal perspective or a safety perspective, the overloading problem of atmospheric pressure tank trucks for dangerous liquids should not be ignored.

[0003] According to statistics from relevant departments, about 20% of the atmospheric pressure tank trucks on the market currently have excessive volumes. To address this problem, a common modification solution is to use a sealed wave-breaking plate to divide the interior of the tank into independent closed compartments to reduce the volume. However, this method has obvious limitations: first, the sealed wave-breaking plate essentially becomes a partition plate, which requires additional pressure resistance and air tightness tests, and the operation is complicated and difficult; second, the volume after modification using this method can only be an integer multiple of a single compartment, which makes it difficult to achieve precise control of the volume and easily leads to a waste of space resources. Summary of the invention

[0004] In order to overcome the above-mentioned problems of the prior art, the purpose of the present invention is to provide a method for modifying an atmospheric pressure tank truck with excessive volume for liquid dangerous goods: first, the actual volume of the tank truck is measured by weighing method, and the modified volume is calculated after comparison with the marked volume, and the position of the opening of the wave-breaking plate is obtained by calculation. A hole is opened at the specified position of the wave-breaking plate, and the vent holes above the opening position are blocked, so that a closed gas phase space is formed above the opening position of the chamber, and the liquid level in the chamber is prevented from rising, and finally the volume is reduced accurately. This method does not require welding operations on the tank body, nor does it change its internal structure. The modification is achieved only by adjusting the position of the vent holes of the wave-breaking plate. Compared with traditional methods, it has the characteristics of simple operation, economic efficiency and strong adaptability.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The transformation method of the normal pressure tank truck for liquid dangerous goods with excessive volume is as follows:

[0007] S1: Obtain the actual volume V of the tank by weighing b .

[0008] S2: Find the volume V marked in the factory data of the atmospheric pressure tank truck a , if (V b -V a ) / V a >3%, the tank volume needs to be modified, and the modified volume is:

[0009] V=V b -V a (1)

[0010] S3: Select the modified chamber according to the volume V that needs to be modified, calculate and determine the distance h between the opening position of the wave-breaking plate and the top of the tank body, make a hole on the wave-breaking plate according to the distance h, seal the gas phase channel on the top of the modified chamber and the air vents above the opening position, construct a closed gas phase space in the chamber, and complete the modification of the atmospheric pressure tank truck with excessive volume.

[0011] The distance from the opening of the modified chamber to the tank top is h, and the volume of the space above the opening is:

[0012]

[0013] When the liquid level of the tank truck exceeds the opening position of the wave-breaking plate, the liquid level in the transformation chamber will no longer rise because the gas cannot be further compressed. At this time, the distance from the liquid level to the tank top is h. r , the volume above the liquid level is the volume to be transformed:

[0014]

[0015] According to the ideal gas state equation V 1 The relationship between V is as follows:

[0016] P 0 ×V 1 =(P 0 +ρgh r )×V (2)

[0017] Among them, P 0 represents standard atmospheric pressure, the unit is Pascal (Pa); ρ represents the density of the filling medium of the atmospheric pressure tank truck, the unit is kilogram per cubic meter (kg / m3); g represents the acceleration of gravity, which is 10N / kg, h r That is, the liquid level difference between the transformed chamber and the adjacent chamber after filling is completed.

[0018] The opening distance h can be calculated by combining equations (1), (7), (8) and (2).

[0019] This method is applicable to the transformation of atmospheric pressure tank trucks with excessive volume, in which the wave-breaking plates, the head or the bulkhead plates and the cylinder can form a closed gas phase space.

[0020] In order to prevent the risk of uncoupling when the tank truck goes uphill, the chamber close to the rear head is given priority for renovation.

[0021] If the transformed volume exceeds the maximum volume that can be transformed in a single warehouse, multiple warehouses can be transformed at the same time.

[0022] The advantages and positive effects of the present invention are:

[0023] (1) Convenient operation. The actual volume of the tank truck is obtained by weighing. After determining the volume to be modified, it is only necessary to drill holes at the specified location and seal the gas phase channel above the drilled part to complete the volume modification and achieve accurate reduction of the tank truck volume.

[0024] (2) High efficiency. This method does not involve welding the tank body, does not change the internal structure of the tank body, and only requires changing the opening position of the vent hole of the wave-breaking plate to achieve volume transformation. After completion, there is no need to conduct pressure resistance test and airtightness test, and the transformation efficiency is high.

[0025] (3) Strong adaptability. The atmospheric pressure tank trucks whose wave-breaking plates, heads or bulkheads and the cylinder can form a closed gas phase space and whose excess volume can be transformed by this method, and the operation technology is easy and has strong adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 To transform the process flow chart;

[0027] Figure 2 The schematic diagram of the transformation process;

[0028] Figure 3 This is a schematic diagram of volume calculation;

[0029] Figure 4 This is the assignment curve diagram of Example 1. DETAILED DESCRIPTION

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and through specific embodiments.

[0031] A method for modifying an atmospheric pressure tank truck for liquid dangerous goods with excessive volume, the steps are as follows:

[0032] (1) Use the weighing method to obtain the actual volume of the tank truck and compare it with the volume marked in the factory data of the tank body. If the measured volume exceeds the volume marked in the factory data by more than 3%, the tank body volume exceeds the standard and needs to be modified. The volume of the atmospheric pressure tank truck that needs to be modified is represented by V, then:

[0033] V=V b -V a (1)

[0034] Where: V a Indicates the volume marked in the factory data of the atmospheric pressure tank truck, m 3 ; V b Indicates the measured actual volume of the tank, m 3 .

[0035] (2) By opening a hole at a distance h from the top of the tank on the wave-breaking plate, when the liquid level reaches the hole position during the filling process of the tank truck, the volume of the enclosed space above the hole is V 1 As the filling progresses, the liquid level in the modified bin continues to rise. When the distance between the liquid level and the tank top is h r When , the liquid level in the transformation position no longer rises, and the volume of the space above the liquid level (i.e. the volume to be transformed) is V. During this process, the gas temperature in the gas phase space above the opening remains unchanged, satisfying the ideal gas state equation, that is:

[0036] P 0 ×V 1 =(P 0 +ρgh r )×V (2)

[0037] Among them, P 0 represents standard atmospheric pressure, the unit is Pascal (Pa); ρ represents the density of the filling medium of the atmospheric pressure tank truck, the unit is kilogram per cubic meter (kg / m3); g represents the acceleration of gravity, which is 10N / kg, h r That is, the liquid level difference between the transformed chamber and the adjacent chamber after filling is completed.

[0038] The enclosed gas phase space formed in the modified warehouse is regarded as a section of a column, and its volume is equal to the product of the bottom area and the height, which is the modified volume V. The bottom area is equal to the cross-sectional area of ​​the atmospheric tank truck, represented by S; the height is equal to the total length of the closed warehouse, represented by L. The length of the closed warehouse L is obtained by looking up the factory data of the atmospheric tank truck. The volume of the enclosed space can be expressed as follows:

[0039] V=S×L (3)

[0040] The cross-section of the tank body of an atmospheric pressure tank truck is generally elliptical or circular. To be universal, the tank body cross-section is analyzed and calculated as an ellipse.

[0041] In the tank cross section, establish Figure 3 The coordinate system shown in the figure, the tank cross section, the ellipse equation is as follows:

[0042]

[0043] Among them, the major semi-axis a and the minor semi-axis b of the ellipse can be known parameters in the factory data of the atmospheric pressure tank truck, and the area calculation equation is as follows:

[0044]

[0045] Volume above the opening:

[0046]

[0047] After filling is completed, the volume above the liquid level of the transformation chamber is:

[0048]

[0049] Since the transformation volume V is a known quantity, the liquid level difference h can be calculated by formula (8): r , and then combined with equations (2) and (7), h can be calculated, which is the drilling position required for the transformation.

[0050] Example 1

[0051] Taking the most commonly used atmospheric pressure tanker tank size on the market as an example, define Figure 4 The specifications and dimensions are (1) a = 1.25m; b = 1m, (2) a = 1.25m; b = 0.75m, (3) a = 1m; b = 0.75m, (4) a = 1m; b = 0.65m, (5) a = 0.9m; b = 0.6m. The length L of the closed chamber under all the above specifications is set to 1.75m.

[0052] By obtaining the equation curve between the transformation volume V and the punching position h under the above five specifications, Figure 4 For the convenience of actual operation, the perforation distance h is set at intervals of 0.02 m according to the curve, and the corresponding transformation volume V is summarized in the range of 0 to 1 m. Table 1 is a data table of perforation distances of tank trucks of common specifications, which is used to verify the results of the present invention.

[0053] Table 1 Common specifications of tank truck drilling distance data table

[0054]

[0055]

[0056]

[0057] Factory data indicates tank volume V a =36m 3 The actual volume V of the tank is measured by weighing b =37.641m 3 , exceeding the marked volume by 4.5583%. If it is higher than 3%, it is considered as excessive volume. The volume that needs to be modified is V = V b -V a =37.641-36=1.641m 3 The cross-sectional dimensions of the atmospheric pressure tank truck are (1) a = 1.25 m, b = 1 m, and the length L of the closed compartment is 1.75 m.

[0058] Step 1: The volume to be modified is known to be V = 1.641m 3 , substitute into formula (8):

[0059]

[0060] Calculate h r =0.5766.

[0061] Step 2: Given V = 1.641, h r =0.5766, substitute into formula (2):

[0062] P 0 ×V 1 =(P 0 +ρgh r )×V,

[0063] Wherein the density ρ is defined by volume and water is used as the medium. 0 Take a standard atmospheric pressure as the value and calculate V 1 =1.734.

[0064] Step 3: Known V 1 =1.734, substitute into formula (7):

[0065]

[0066] The calculation shows that h = 0.6. That is, the operator ensures that the opening of the wave-breaking plate is 0.6m away from the tank top, and the transformation is completed.

[0067] Result verification: Look up Table 1. If you want to transform 1.641m under this size 3 The volume of the wave-breaking plate corresponds to a distance of 0.60 between the opening position of the wave-breaking plate and the tank top, that is, the operator ensures that the opening position of the wave-breaking plate is 0.6m away from the tank top, which is basically consistent with the opening position obtained by the transformation method of the present application.

Claims

1. A method for modifying a normal pressure liquid dangerous goods tanker with excessive volume, characterized in that: The steps are: S1: Obtain the actual volume V of the tank by weighing b ; S2: Find the volume V marked in the factory data of the atmospheric pressure tank truck a , if (V b -V a ) / V a >3%, the tank volume needs to be modified, and the volume to be modified is: V=V b -V a (1) S3: Select the modified chamber according to the volume V that needs to be modified, calculate and determine the distance h between the opening position of the wave-breaking plate and the top of the tank body, make a hole on the wave-breaking plate according to the distance h, seal the gas phase channel on the top of the modified chamber and the air vents above the opening position, construct a closed gas phase space in the chamber, and complete the modification of the atmospheric pressure tank truck with excessive volume.

2. The method for modifying a normal pressure liquid dangerous goods tanker with excessive volume according to claim 1, characterized in that: The distance from the opening of the modified chamber to the tank top is h, and the volume of the space above the opening is: When the liquid level of the tank truck exceeds the opening position of the wave-breaking plate, the liquid level in the transformation chamber will no longer rise because the gas cannot be further compressed. At this time, the distance from the liquid level to the tank top is h. r , the volume above the liquid level is the volume to be transformed: According to the ideal gas state equation, V1 and V have the following relationship: P0×V1=(P0+ρgh r )×V (2) The opening distance h can be calculated by combining equations (1), (2), (7) and (8).

3. The method for modifying a normal pressure tank truck for liquid dangerous goods with excessive volume according to claim 1 is characterized in that: The tank truck is a normal pressure tank truck in which a wave-breaking plate, a head or a partition plate and a cylinder body can form a closed gas phase space.

4. The method for modifying a normal pressure tank truck for liquid dangerous goods with excessive volume according to claim 1 is characterized in that: In order to prevent the risk of uncoupling when the tank truck goes uphill, the chamber close to the rear head is first modified.

5. The method for modifying a normal pressure tank truck for liquid dangerous goods with excessive volume according to claim 1 is characterized in that: If the transformed volume exceeds the maximum volume that can be transformed in a single warehouse, multiple warehouses can be transformed at the same time.

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